Host devices such as smartphones, electronic tablets, and the like typically include one or more accessory ports. For instance, many host devices provide universal serial bus (USB) accessory ports. Host devices from Apple, Inc. include a proprietary accessory port known as the Lightning® port. Such accessory ports may have the ability to provide power from the host device to the accessory that is connected to the accessory port. In some cases, the accessory port may be able to utilize a single electrical connection to supply power and to receive power, and the accessory port is placed into one mode or the other by the accessory controlling a voltage state of a separate electrical connection. A USB port with an on-the-go feature set is one example.
While being able to power an accessory from the host device provides the advantage of no on-board battery for the accessory, there are also disadvantages. Conventionally, when an accessory is of the type that draws power from the accessory port of the host device, the accessory draws power the entire time it is connected to the accessory port of the host device. When the host device is battery powered, as is often the case since many host devices are of a portable nature, the accessory can excessively increase the rate of battery discharge of the host device. This is particularly troublesome for accessories that are intended to remain attached to the accessory port of the host device most of the time, as the amount of time that the host device may function on a single recharge of the battery may be reduced by an amount considered unacceptable by the user.